Fluid heater



Oct. 14, 1958 c. 51.155 2,855,903

FLUID HEATER F iled Oct. 25, 1955 1 3 Sheets-Sheet l Zmnentor q CAM/PL 5 BL I55 {,s s C W. M

attorney c. BLISS FLUID HEATER Get M, 1958 3 Sheets-Sheet 2 Filed 001:. 25, 1955 Cmmas Buss (Ittorneu 0. BLISS FLUID HEATER 5 Sheets-Sheet 3 Filed Oct. 25 1955' (Ittorneg FLUID rmATER Charles Bliss, Dobbs Ferry, N. Y., assignor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application October 25, 1955, Serial No. 542,731

8 Claims. (Cl. 122149) This invention relates to fluid heaters and more particularly to direct fired fluid heaters.

Generally, in direct fired tubular heaters the fluid to be heated is conducted .through tubular members which are arranged in the path of flow of a heating fluid, as for example combustion gases, whereby the fluid to be heated passes in heat exchange relationship with the combustion gases. The temperature to which the fluid to be heated may be raised is limited in one respect, by the availability of tube materials which can withstand the relatively high temperatures. In cases where the fluid to be heated has a relatively low thermal conductivity, as for example air or water, the amount of heat absorbed by the fluid under high temperature conditions is not sutficient to prevent overheating of and consequent failure of the tubular members carrying the fluid. In many instances, the final temperature of the fluid to be heated must be restricted below that desired because of the problems of tube overheating.

It is an object of the present invention to provide a fluid heater which operates at maximum efliciency and in which the fluid to be heated may be raised to relatively high temperatures.

The present invention, therefore, contemplates a novel fluid heater wherein aplurality of tubes are provided with burner means which fire into the tubes to direct the resulting combustion gases internally thereof, and a fluid to be heated is conducted over the outside of the tubes in heat exchange relationship with the combustion gases therein. The fluid heater is provided with means which effect the preheating of combustion air by the combustion gases and the passage of the heated combustion air to the burner means.

The invention will be better understood from the fol-- lowing description when considered in connection with the accompanying drawings, in which:

Fig. 1 is a side elevational view of a fluid heater embodying the present invention;

Figs. 2 and 2A are sectional'views, in elevation, of the left and right halves, respectively, of the fluid heater seen in Fig. l. I

' Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2.

Referring now to the drawings for a more detailed description of the present invention wherein one embodiment hereof is clearly illustrated, a fluid'heater, generally designated by the numeral 11,'is shown as comprising a substantially cylindrical shell 12 mounted on spaced support means 13. A plurality of burners 14 are mounted at the left end of shell 12 (as seen in Fig. 2) and the burners extend into an annular chamber 15 formed in a housing 16. Associated with each burner 14 is a fluid carrying tubular member 17 which extends longitudinally of the shell and adjacent the periphery thereof. The opposite ends of tubes 17 are supported in annular tube sheets 18 and 19, respectively, arrangedat the ends of the shell ,12 and the tubes extend slightly beyond the tube rates Patent 6 ice sheets. The nozzle portions of burners 14 in chamber are spaced from the tubes 17 and are positioned to fire into the tubes whereby the resultant combustion gases are directed internally of the tubes. Tubes 17, as well as burners 14, are spaced circumferentially in a circular manner. A fuel connection 14A is provided for each burner 14 to connect the latter with a source of fuel (not shown) as for example, oil.

The ends of tubes 17 projecting beyond annular tube sheet 19 (Fig. 2A) extend into a chamber 20 of a housing 21 secured to shell 12. The combustion gases in tubes 17 enter chamber 20 and flow into a plurality of tubular members 23 which extend longitudinally within shell 12. Tubular members 23 are similarly supported as tubes 17, in annular tube sheets 18 and 19 and are arranged in a circular row which is concentric with the row of tubes 17. The diameter of tubes 23 is less than that of tubes 17 and the ends of tubes 23 project slightly beyondannular plate member 18 into a chamber 24, adjacent chamber 15. The combustion gases flowing through tubes 23 enter chamber 24, thence flow into a bundle of tubular members 25 which extend longitudinally within shell 12. Tubes 25 are arranged in a plurality of concentric circular rows which are concentric with the rows of tubes 17 and 23 and the opposite ends of tubes 25 are supported in a pair of annular tube plates 26 and 27, respectively. The combustion gases flowing through tubes 25 enter a chamber 23 of a housing 29 which communicates with a stack 30 (Fig. 1) by way of a conduit 31, whereby the combustion gases are discharged from the fluid heater.

A cylindrical member 32 is provided within shell 12 and is' arranged concentric therewith to define an outer compartment 33 and an inner compartment 34; compartment 33 containing the tubes 17 and 23 and compartment 34 containing tubes 25. A inlet 35 is provided in the upper portion of shell 12, adjacent tube sheet 18, in communication with compartment 33. Inlet 35 is adapted for connection to a source (not shown) of fluid to be heated, which fluid has a relatively high thermal conductivity and in the present embodiment is preferably a liquid metal, as for example liquid sodium having a thermal conductivity of 38 B. t. u.-ft./(hr.) (sq. ft.) F.) The liquid sodium enters compartment 33 through a perforated flow distributing circular baflle 36 which extends approximately midway of the shell 12 and surrounds portions of tubular members 17 and 23. A pair of ring-shaped baffles 37 (Fig. 2) and 38 (Fig. 2A) are arranged in compartment 33 transversely of shell 12. The outer edge of baffie 37 is secured in fluid-tight relationship to shell 12 while the inner edge of bathe 37 is spaced a slight distance from cylindrical member 32. Ring shaped bathe 38 is spaced from and arranged parallel with bathe 37, and the outer and inner edges of baflie 38 are spaced from shell 12 and cylindrical member 32, respectively. A longitudinally disposed cylindrical member 39 is arranged in between the rows of tubes 17 and 23, concentric with shell 12 and cylindrical member 32, and the opposite edges of cylindrical member 39 are secured to bafiles 37 and 38, respectively. Cylindrical member 39 cooperates with battles 3'7 and 38 to define a pair of annular chambers 40 and 41; chamber 40 containing portions of tubular members 17 and chamber 41 containing portions of tubes 23. An annular batlle 42 (Fig. 2) is arranged in chamber 41 midway of bafiles 37 and 38 and the inner edge of battle 42 is secured to cylindrical member 32 while the outer edge of the battle is spaced from cylindrical member 39. A similar annular baffle 43 is arranged in chamber 40, coplanar with bafile 42 and midway of bafiles 37 and 38. The outer edge of baflie 43 is secured to shell 12 and the inner edge of the bafile is spaced from circular cylindrical member 39.

The sodium in the space between annular tube plate 18 and bafile 37 passes therefrom through a space between the inner edge of member 37 (Fig. 2) and cylindrical member 32 and enters the portion of chamber 41 bounded by baffles 37 and 42. The sodiumtthenflows. into the'other portion of compartment 41 through the space between the outer edge of baffle 42 and cylindrical member 39 whence it leaves chamber 41 throughv the. space between the inner edge of baffle 38 and cylindrical member 32 (Fig. 2A). The sodium in the part of compartment 33 bounded by baflle 38 and annular tube, plate 19 flows over the outer edge of baffle 38 into that part of chamber 40 bounded by baflles 43 and 38. From the last-mentioned part of chamber 40 the sodium passes through the space between the inner edge of annular baffle 43' and cylindrical member 39 into the other portion of chamber 40 defined by baffles 37 and 43. An outlet 45 is provided in the upper portion of shell 12, adjacent baflle 37, and communicates with chamber 40 to provide for discharge of heated liquid sodium from shell 12.

A circular passageway 46 is provided in housing 29 and in fluid-tight relationship with chamber 28. Passageway 46 communicates, by way of a conduit means 47 (Fig. l), with a centrifugal blower 48 which is connected at its suction side to the atmosphere. Air at a pressure slightly above atmospheric is directed through passageway 46 into a circular passageway 49 which comprises the central portion of compartment 34. Baffles 50 are provided in compartment 34 and serve to direct the air over the tubular members 25, countercurrent to the combustion gases flowing in the tubes. In passing, over the tubes 25, the air is heated and then is discharged from the compartment 34 through an opening 51 in annular tube sheet 26 whence the preheated air flows into a chamber 52 in housing 16. Chamber '52 has conneeted thereto a plurality of conduits 53 which are connected at their other ends to burners 14 to thereby provide the latter with preheated combustion air.

In operation, burners 14 are fired and direct the resulting combustion gases into tubes 17. The combustion gases in tubes 17 leave the latter and enter chamber 20 thence tubes 23, and flow through the latter to chamber 24. From chamber 24 the combustion gases pass through tubes 25 thence into chamber 27 and out to the stack 30 through conduit means 31. The liquid sodium is introduced through inlet 35 into compartment 33 over the perforated baflle 36 which evenly distributes the sodium over the tubes 17 and 23. The sodium then leaves the portion of compartment 33, bounded by annular plate 18 and baflle 37, and enters compartment 41 wherein the sodium is in heat exchange relationship with tubes 23 only. From compartment 41 the sodium enters the portion of compartment 33 adjacent annular tube plate 19 where it passes in heat exchange relationship with both tubes 23 and 17. The sodium then passes into compartment 40 where it flows in heat exchange relationship with tubes 17, only. The sodium is discharged from compartment 40 through perforated flow bafile 36 and outlet 45. The discharged heated liquid sodium may then be conducted to other apparatus where it may be used for such purposes as heating another fluid, if desired.

Cold combustion air is drawn through blower 48 and conduit 47 whence it passes through chamber 46 into central passageway 49. The combustion air passes in countercurrent flow relationship with the combustion gases flowing through tube 25. As shown in Fig. 2 by the curved arrows, batfles 56 cause the combustion air to flow alternately across the tubes 25 and in central passageway 49. The combustion air thus heated passes through outlet 51 of annular plate member 26, thence into chamber 52 where it is conducted through conduits 53 into the burners 14 to provide the latter with preheated combustion air.

It will now be apparent that the present invention provides a novel fluid heater wherein burner means may be employed to fire directly into tubular members. This is possible because of the utilization of a fluid which has a relatively high thermal conductivity; thus large amounts of heat may be absorbed by the fluid to thereby prevent overheating of the tubular members.

Although one embodiment of the present invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in. the art.

What is claimed is:

1. In a fluid heater of the class described, a cylindrical shell having an inner and an outer concentric compartment extending longitudinally of the shell, a plurality of tubular members arranged in said outer compartment and extending longitudinally therein, burner means disposed to fire into the tubular members to direct the resulting combustion gases internally of the latter, inlet means in said shell for introducing a fluid to be heated into said outer compartment for passage in heat exchange relationship with the combustion gases in said tubular members, outlet means in said shell for discharging fluid to be heated from said outer compartment, a plurality of second tubular members arranged in said inner compartment and extending longitudinally thereof, means communicating the first-mentioned tubular members with.

the second tubular members to provide the latter with combustion gases therefrom, second inlet means in said;

shell for introducing combustion air into the inner com partment in heat exchange relationship with the combustion gases within the second tubular members, and means communicating the burner means with said inner compartment for supplying the burner means with the combustion air.

2. In a fluid heater of the class described, a cylindrical shell divided into a pair of longitudinally extending compartments, a plurality of circumferentially arranged tubular members disposed in one of said pair of compartments, burner means arranged to fire into said tubular members to direct the resulting combustion gases internally of the latter, a plurality of circumferentially spaced second tubular members in said one compartment and disposed concentric with said first-mentioned tubular members, said second tubular members being in communication with said first tubular members for receiving combustion gases therefrom, inlet means in said shell for introducing into said one compartment a fluid to be heated in heat exchange relationship with the combustion gases in both said first and second tubular members, means for discharging said fluid to be heated from said one compartment, a plurality of third tubular members arranged in said other compartment concentric with said first and said second tubular members, said third tubular members being in communication with said second tubular members for receiving combustion gases therefrom, means for introducing combustion air into said other compartment and in heat exchange relationship with the combustion gases flowing in said third tubular members, and means communicating said other compartment with said burner means to provide the latter with preheated combustion air.

3. The fluid heater set forth in claim 2 wherein the diameter of the second tubular members in less than that of the first tubular members, and the diameter of the third tubular members is less than that of the second tubular members.

4. In a fluid heater of the class described, a cylindrical shell divided into fluid-tight concentric inner and outer longitudinally extending compartments, a pair of concentric rows of tubular members extending longitudinally of said shell in said outer compartment, means in said outer compartment arranged intermediate said shell for separating the latter into axial compartments including a pair of end compartments and an intermediate compartment containing said pair of rows of tubular members, burner means at one end of one of said end compartments and disposed to fire into the adjacent ends of one row of tubular members to direct the resulting combustion gases internally of the latter, means communicating the ends of both rows of tubular members at said other end compartment to provide for passage of combustion gases into said other row of tubular members, inlet means in said shell for introducing into said one end compartment a fluid to be heated in heat exchange relationship with the combustion gases in both tubular members disposed in said one compartment, means separating said intermediate compartment into a pair of concentric chambers with portions of said one row of tubular members in one of said chambers and portions of said otherrow of tubular members in the other of said chambers, means communicating said one end compartment with said other chamber and the latter with the other end compartment to provide for passage for the fluid to be heated from said one end compartment through the other chamber to the other end compartment, means communicating said other end compartment with said one chamber to provide for passage of fluid to be heated from said other compartment to said one chamber, outlet means for discharging the fluid to be heated from said one chamber and from the shell, and second outlet means for discharging the combustion gases from the shell.

5, The fluid heater set forth in claim 4 wherein the one row of tubular members is arranged at a greater radial distance from the axis of the shell than the other row of tubular members.

6. The fluid heater set forth in claim 4 wherein the said second outlet means comprises a plurality of third tubular members arranged in said inner longitudinally extending compartment; means are provided for communicating the other row 0! tubular members with the third tubular members to provide for passage of com-,

bustion gases thereto; air inlet means introduce combustion air into the shell in heat exchange relationship with the combustion gases in the third tubular members; and means in communication with the burner means and the inner longitudinally extending compartment to supply the burner means with the preheated combustion air.

7. The fluid heater set forth in claim 4 wherein the means arranged intermediate the shell for separating the latter into axial compartments comprises a pair of spaced and radially extending baflles which define the intermediate compartment therebetween.

8. The fluid heater set forth in claim 7 wherein the means separating said intermediate axial compartment into a pair of concentric chambers comprises a cylindrical member concentric with and spaced from the shell, the opposite edges of said cylindrical members being secured in fluid-tight relationship with said radially extending baflles.

References Cited in the file of this patent UNITED STATES PATENTS 332,941 Pessenger Dec. 22, 1885 577,240 Edgar Feb. 16, 1897 1,798,330 Leek Mar. 31, 1931 2,062,321 Levin Dec. 1, 1936 2,314,089 Hess et al. Mar. 16, 1943 2,383,924 Way et al. Aug. 28, 1945 2,532,527 Woolery Dec. 5, 1950 2,625,138 Jacoby Jan. 13, 1953 FOREIGN PATENTS 22,236 Great Britain 1891 6,220 Great Britain 1832 

